The present invention relates generally to water treatment tanks of the type used to retain resin beads in a water softener system. More particularly, the present invention includes an improved tank head and flange for simultaneously connecting to a control valve, being the securing point for a tank liner, and retaining a water outlet manifold.
Water treatment tanks are known and used to condition or soften water. The known tanks have a tank head that provides an inlet and an outlet for the water through penetration fittings or collars. The known tanks also have liners to protect the tanks from corrosion and prevent leaching of materials from within the tank. In these conventional tanks, water enters the tank through an inlet, flows to the bottom of the tank while passing through a softening or treatment material, and then enters a manifold near the bottom of the tank to be brought back to the top of the tank, where the treated water exits the tank through an outlet conduit connected to a valve. Examples of such tanks are disclosed in commonly owned U.S. Pat. Nos. 5,174,466 and 5,345,666, which use one central opening with concentric collars and eliminates the need for a gasket.
For the type of conventional tank that uses concentric collars, such as that disclosed in the '466 and '666 patents, an outer collar is welded to the tank head and a nut is tightened to secure an inner collar to the outer collar and the tank head. Since one of the collars must be welded, it is more difficult to disassemble the tank for maintenance. In addition, problems occur when tightening the nut on the inner collar since the inner collar can rotate while rotating the nut.
In other types of known tanks, direct compression gaskets are used but become ineffective due to "compression set" in the gaskets over age. Thus, the tanks of the '466 and '666 patents were designed to eliminate the gasket. To eliminate the gasket, however, required a complex design with a number of separate parts. O-rings replaced a gasket to create a hermetic seal between the concentric collars. Also, in this design, the outer collar must be under compression and the inner collar receives upward pressure to maintain the tight seal.
In center opening type tanks, such as disclosed in the '466 and '666 patents, the opening of the protective liner is attached to an inner surface of an inner collar. This arrangement places the edge of the liner inside the inlet aperture for the tank. In this position, it is extremely difficult and time consuming to weld the liner to the inside of the collar because the position of the liner-collar joint requires cumbersome positioning of the welding tools. The liner also may become susceptible to peeling away from the flange from the force of the incoming water flow.
Also in the center opening type tanks, one large central opening on the tank head provides concentric pathways for the inlet and outlet. A valve connected to the tank head provides corresponding concentric inlet and outlet passages. The inlet passage is donut shaped while an outlet conduit forms the center of the donut shape and connects to the manifold in the tank.
When the control valve is lifted from the tank head for service, the outlet conduit often remains connected to the manifold so that the manifold is pulled out of the tank upon removal of the valve. Due to the density of gravel underbedding located beneath the resin beads in the tank, it is extremely difficult to push the manifold back into the tank without first emptying the tank, which wastes time and resources.
Finally, other types of tanks have sensor probes or other equipment to test water or solutions sitting in the tank. An example of such a tank is disclosed in commonly owned U.S. Pat. No. 5,699,272. This type of tank requires an opening in the tank head reserved for the probe. For both the probe opening and the main central opening, when cylindrical valve attachment collars are secured to circular tank openings with a nut, the collars are difficult to secure because the collars tend to rotate when rotating the nut.
Thus, a main object of the present invention is to provide an improved center opening tank which is easier to assemble and maintain than presently known tanks.
Yet another object of the present invention is to provide an improved center opening tank with a flange that is not welded to the tank and which cannot rotate upon tightening a nut on a nipple portion of the flange for more efficient assembly of the tank.
Still another object of the present invention is to provide an improved center opening tank with an opening designed for mounting the flange on the internal side of the tank.
Yet another object of the present invention is to provide an improved center opening tank with a domed tank head to provide a stronger tank head.
An additional object of the present invention is to provide an improved center opening tank that retains the liner in a position easier to attach to a flange while away from the apertures in the flange with an improved retaining surface to prevent breaks in the seal between the liner and the flange.
Still a further object of the present invention is to provide an improved center opening tank that retains the manifold in the tank during control valve removal.